Researchers from the Centre d’Estudis Avançats de Blanes (CEAB-CSIC) in collaboration with the Estación de Investigación Jaume Ferrer (GOIB-IEO) and the Observatori Socioambiental de Menorca (OBSAM-IME) describe for the first time the presence in Menorca waters of the pearl oyster Pinctada imbricata radiata (Leach, 1814), an introduced species from the Red Sea.
The study, led by Dr. Enric Ballesteros from CEAB-CSIC, discusses various aspects related to its introduction, such as date of colonization, size of individuals, densities and preferred habitat. To do this, shallow seabeds have been surveyed in three locations on the Menorcan coast: the port of Mahón, the Bay of Addaia and the Bay of Fornells, identifying their presence in 4 of the 22 stations sampled. Although the oysters have been located in different places where surveys have been made, at the moment the number of registered individuals is not sufficient to be able to assign the label of invasive species. Even so, it is not ruled out that in the future its proliferation in these waters may become significant enough to achieve this status.
Although the densities observed in Menorca are very far from those of an invasive species, the population identified in the port of Mahón can be considered as the second well established in the Western Mediterranean. However, the dispersal capacity that the species will show in the coming years is unknown, since the oceanographic conditions of Menorca are far from those of other areas of the eastern basin where this species has reached invasive status ”, says Enric Ballesteros from CEAB-CSIC.
Observing the sizes of the individuals found, and the observations provided by an observer from the port of Mahón, the study concludes that this new species may be present in the waters of Menorca since approximately 2016 and as explained by the Boletín de la Sociedad de Historia Natural de Baleares. As it is a recent introduction, its possible future expansion should be monitored, since this species shows a high invasive potential in various locations in the Eastern Mediterranean. Even so, data such as the date of colonization, the size of the individuals, the density and their preferred habitats, among other collected data, will allow us to obtain more information about the introduction processes of this pearl oyster in the waters of Menorca.
It is necessary to remember that this species has been documented in the Mediterranean since 1874, specifically on the shores of Alexandria, being one of the first known species from the Red Sea. In the last 40 years its presence has been reported in very localized places in the Adriatic, in Liguria, in the Strait of Messina, Corsica, Sardinia, Majorca and also in Catalonia. More recently it has also been detected in the Ebro Delta.
Ballesteros, E., Marsinyach, E., Bagur, M., Sales, M., Movilla, J., Bolado, I., Cefalì, M.E. 2020. The pearl oyster Pinctada imbricata radiata (Leach, 1814) (Bivalvia: Pteriidae) reaches Minorca, Balearic Islands. Boll. Soc. Hist. Nat. Balears, 63: 97-108.